\documentclass{standalone}
\usepackage{tikz}
\usepackage{ctex,siunitx}
\setCJKmainfont{Noto Serif CJK SC}
\usepackage{tkz-euclide}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{circuitikz}
\usetikzlibrary{patterns, calc}
\usetikzlibrary {decorations.pathmorphing, decorations.pathreplacing, decorations.shapes}
\ctikzset{bipoles/length=1cm}
\begin{document}
\small
\begin{circuitikz}[>=latex, scale=0.9,european]
  % \useasboundingbox(0.9,0)rectangle(5.1,5);
  \fill[cyan!20!lightgray,opacity=0.3,draw=black,rounded corners=2mm](-2,-0.2)rectangle(2,0.2);
  \draw[thick](-1.8,-0.1)--(-1.8,0.1)(1.8,-0.1)--(1.8,0.1);
  \foreach \x in {-1.8,-1.2,-0.6,0,0.6,1.2,1.8}
    {
      \draw[very thin,densely dashed](\x,-0.1)--(0.1*\x,0.4);
    }
  \draw(-0.6,0.4)rectangle(0.6,0.6);
  \node at(0,0.6) [above]{电离剂};
  \node at (0,-3.2) {$R$};
  \node at (0,-4) {接高压电源};
  \draw(-1.8,0)--(-3.0,0)to[rmeter,t=A](-3.0,-1.5)--(-3.0,-3.5)[-o]--(-0.5,-3.5)node[below]{\scriptsize$+$};
  \draw(3.0,-2.7)--(3.0,-3.5)[-o]--(0.5,-3.5)node[below]{\scriptsize$-$};
  \draw(-3.0,-1.5)to[rmeter,t=V,*-*](3,-1.5);
  \draw(-3.0,-2.7)to[pR,name=hb,*-](3,-2.7);
  \draw(1.8,0)--(3.0,0)--(3.0,0|-hb.wiper)--(hb.wiper);
\end{circuitikz}
\end{document}